Portable bookend



FIG. 1 is a front elevational view of the portable bookend showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a right view thereof;

FIG. 4 is a left view thereof;

FIG. 5 is a top plan view thereof; and,

FIG. 6 is a bottom plan view thereof. 

The ornamental design for portable bookend, as shown and described. 